<!DOCTYPE html>
<html lang="zh-CN">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>选择器的权重</title>
    <style>
        /* !important > 行内 > id > class > element */
        div{
            background-color: yellow;
        }
        .box{
            background-color: red;
        }
        #box_id{
            background-color: blue;
        }
    </style>
</head>
<body>
    <div class="box" id="box_id" style="background-color: green;">11111111111</div>
</body>
</html>